The
night sky in the World

Satellite
monitoring of the artificial night sky brightness and the stellar
visibility

The
interest for the protection of the night sky from light pollution is growing
every day. A global scale periodic monitoring of the situation is necessary.

Nighttime
images of the Earth at night have been obtained from the Defense Metereological
Satellite Program (DMSP) of the US Air Force since early '70. The first
global image was obtained by Woodruff Sullivan in late '80.

These
images only showed thegeographic distribution of the sources on the Earth
surface because the satellite detectors were saturated by the strong flux
emitted by them and no quantitative measurements were possible.

However
satellite data don’t give any direct information on the effects of this
light flux on the night sky due to light pollution propagation. The aim of our
work is to study these effects.

We
measure the upward light flux of sources on the Earth surface based on DMSP
satellite data and then we compute the effects on the night sky modelling the
light propagation in the atmosphere.

Depending
on the kind of map, we account for many details like the scattering of light by
molecules and aerosols, the extinction along light paths, the atmospheric
aerosol content, the Earth curvature, the altitude of each area, the mountain
screening, the observed sky direction, the natural sky brightness, the stellar
extinction, the eye capability.

In
this site you can find information on our work, maps, scientific publications.